1. Field
The present invention relates to an image display apparatus that controls a pointer to be displayed on a display, and a pointing method performed by the image display apparatus.
2. Description of Related Art
If a website is browsed via a TV, a TV remote controller including a pointing function may be used to click a link or the like.
This remote controller includes a motion sensor such as an acceleration sensor or an angular velocity sensor, and is configured to detect a posture angle variation of the remote controller from outputs of these sensors and convert a pointing angle calculated from the detected posture angle variation into a pointer position on a display (see Patent Document 1). This case is referred to as a relative pointing method, because the pointer position on the display is accumulatively calculated based on the posture angle variation of the remote controller.
However, in pointing devices using the relative pointing method, a direction in which a remote controller points may be largely different from a pointer position on a display, and thus users may fail to have natural usage feeling. This phenomenon occurs due to a change in a relationship between relative positions of the display and the remote controller or accumulation of posture errors of the remote controller that are estimated by a motion sensor.
A conventional pointing device will now be illustrated and described in detail. As shown in FIG. 35, a remote controller 200 including an angular velocity sensor and operating based on a relative pointing method horizontally moves a pointer position on a screen by horizontally changing a pointing direction PD, in which a leading end of the remote controller 200 points.
In more detail, a standard direction SD is set in the remote controller 200, and a pointer position on a display 100 is determined according to a pointing angle formed by the pointing direction PD with respect to the standard direction SD.
A manipulating angle range CR is set as a predetermined solid angle having the standard direction SD as its center according to a predetermined correspondence relationship with a pointing range on the display 100 of FIG. 35. For example, when the manipulating angle range CR is set to be narrow, a pointer is sensitive to a motion of the remote controller 200, and, when the manipulating angle range CR is set to be wide, the pointer is dull to a motion of the remote controller 200.
In other words, when the standard direction SD matches the pointing direction PD, the pointer is disposed on the center of a screen of the display 100. When a pointing angle exists, a pointer position on the display 100 is changed according to the set manipulating angle range CR.
In FIG. 35, P1 indicates a case where the remote controller 200 is located in the front direction of the display 100. In this case, the standard direction SD, which is the center of the manipulating angle range CR, perpendicularly faces a screen center PO. When the standard direction SD matches a direction perpendicular to the screen center P, the pointing direction PD of the remote controller 200 favorably matches the pointer position, and thus users may have a natural usage feeling.
When a user has moved rightwards according to setting of P1 of FIG. 35, as shown in P2 of FIG. 35, the standard direction SD faces a right end of the display 100. When the pointing direction PD of the remote controller 200 also faces the right end of the display 100 so as to match the standard direction SD as indicated by P2 of FIG. 35, the pointer is not displayed on the right end of the screen but on the screen center according to the setting of P1 of FIG. 35. As such, the pointing direction PD of the remote controller 200 greatly mismatches with the pointer position, and thus users feel it is unnatural.
When this mismatch occurs, a conventional pointing device compulsorily makes the pointing direction of the remote controller match with the pointer position through a user directing the remote controller toward the screen center and then pressing a reset button. Alternatively, there is a pointing device configured such that a pointer stops when moving to an end of a display, and that a user is able to adjust a pointing direction of a remote controller to match with a pointer position on a screen end.
There have been proposed several techniques of moving a display position of a pointer on a display according to a movement of a remote controller (for example, see Patent Documents 2-4). In the technique of Patent Document 2, when an optic-type pointing device is moved, a light-receiving device moves a display position of a pointer according to a position signal obtained by calculating a variation of a light-receiving signal. In the technique of patent document 3, a TV compares the coordinate of an imaging cursor image included in an image captured by a camera of a remote controller with the coordinate of a display cursor image displayed at this time and generates a cursor image that is to be displayed at a detected remote control pointing position on a display screen. In the technique of patent document 4, when a pointing button of a manipulator is touched, a TV set displays a cursor at a position on the TV screen according to a remote control angle obtained from a light-receiving intensity of infrared light emitted from 4 light-emitting diodes (LEDs).